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Heavy rain spurs rare October rise for Lake Superior

The level of Lake Superior rose two inches in October, a month the big lake usually drops 2 inches. Continued high water levels are expected to add to shoreline erosion if November storms hit. News Tribune file photo.

An "exceptional amount" of rainfall fell across the Lake Superior basin Oct. 8-11, spurring a rapid increase in water level and sending the big lake up 3 inches for a month it usually drops 2 inches.

The International Lake Superior Board of Control said the rare October water level increase sent the lake to 11 inches above the normal Nov. 1 level.

Lake Superior is 2 inches below the Nov. 1 level of last year, when November storms wreaked havoc along shorelines. But the lake is still very high for this time of year and U.S. Army Corps of Engineers hydrologists warn that shoreline erosion is still likely if big storms hit.

"The above-average levels coupled with strong winds and waves continue to result in shoreline erosion and coastal damages across the upper Great Lakes system,'' the board noted in its monthly report released Friday.

The board has approved opening more gates at Lake Superior's outlet, sending the St. Mary's River into a torrent through November with an average flow of 44,637 cubic feet per second expected, the highest flow since 1996.

Lake Superior usually drops September through March and then rises April through August.

Conditions were relatively wet in the Lake Michigan-Huron basin, too, the board reported. The lakes dropped just under 1 inch in October when on average they drop 3 inches. The lakes are a whopping 18 inches above normal for Nov. 1 but about 1 inch below the Nov. 1 level last year.